Removal of contaminants from unsaturated hydrocarbon-containing mixtures



United States Patent 3,299,163 REMGVAL 0F (IQNTAMHNANTS FRUM UN-SATURATED HYDRQCARBUN-CQNTAHNHNG MlXTUl'tES Robert P. Zelinslri,Bartlesville, Okla, assignor to Phillips Petroleum Company, acorporation of Delaware No Drawing. Filed Aug. 30, 1965, Ser. No.483,846 Claims. (Cl. zen-eats This invention relates to the purificationof unsaturated hydrocarbon-containing mixtures to remove undesirablecontaminants therefrom. In accordance with one aspect, the inventionrelates to a method of removing unsaturates such as 1,2-dienes andl-acetylenes from conjugated diene mixtures containing same bycontacting the mixture at an elevated temperature with an alkali metalhydroxide solution of glycol, amine, or thiol, or mixtures thereof. Inaccordance with another aspect, the invention relates to apolymerization process in which the conjugated diene to be polymerizedis pretreated with an alkali metal hydroxide solution of a glycol, amineor thiol or mixtures thereof prior to contact with the polymerizationcatalyst. The removal of contaminants such as 1,2-dienes and acetyleniccompounds from conjugated diene-containing streams, especially1,3-butadiene has been a major problem in the industry and has receivedmuch consideration. Hydrogenation followed by extensive fractionationhas been employed to remove or reduce the quantities of these materialspresent in by-product butadiene, for example, such as that obtained fromnaphtha cracking operations.

The present process provides a method whereby 1,2- dienes such as alleneand 1,2-butadiene, and l-acetylenes such as vinylacetylene,methylacetylene, 1-butyne and the like can be removed from conjugateddiene mixtures containing them without the necessity for hydrogenationand extensive fractionation. There is thus provided a means whereby asubstantial reduction in plant investment and utilities is realized.

Accordingly, an object of this invention is to provide a simplifiedprocess for removing contaminants from unsaturatedhydrocarbon-containing mixtures such as polymerization feeds.

Another object of this invention is to provide an improved process forremoving 1,2-dienes and l-acetylenes from conjugated diene-containingmixtures to provide a highly purified conjugated diene-containingstream.

A further object of this invention is to provide a process forpolymerizing conjugated dienes in which the conjugated dienes arepretreated prior to contact with the polymerization oatalyst so as tothereby obtain rubbery polymer products having desirable physicalproperties.

Other and further objects and advantages of this invention will becomeapparent to those skilled in the art by the consideration of theaccompanying disclosure and the appended claims.

According to the invention, unsaturated hydrocarboncontaining mixturessuch as conjugated 1,3-diene mixtures containing 1,2-dienes andl-acetylenes are contacted at a temperature of at least 100 C. with analkali metal hydroxide solution of a compound selected from glycols,amines, and thiols, and mixtures of these to effect a substantialreduction in quantities of the compounds containing 1,2-dienes and1acetylenes. The process is of particular importance for removingcompounds such as allene, 1,2-butadiene, vinylacetylene,methylacetylene, and l-butyne from butadiene-containing mixtures.

In actual operation, contacting of a conjugated dienecontaining mixtureto remove 1,2dienes and l-acetylenes can be effected by any suitablemethod known in the art. The mixture to be treated can be in either thegaseous or liquid phase and any necessary pressure adjustments made forseparation of the monomer from the treating solution.

3,Z9,ll53 Patented Jan. 17, 1967 One convenient method is to introducethe conjugated diene mixture in the gaseous state into the treatingsolution in the column or other suitable arrangement. The process isfrequently conducted in a series of contactors or treating columns, eachcontaining a portion of the treating solution, in order to facilitatecontact with the material being treated.

According to the invention, solutions of one or more alkali metalhydroxides in a glycol, amine, or a thiol, or mixtures of any of thesematerials, as more fully described hereinafter, are employed as treatingagents. While any of the alkali metal hydroxides can be employed, sodiumhydroxide and potassium hydroxide are presently preferred. Thus, alkalimetal hydroxides dissolved in glycols, primary amines, secondary amines,polyamines, monothiols, dithiols, and mixtures of any of these materialsare applicable as treating agents in this inven tion. The solventsemployed preferably have a boiling point of at least C. at atmosphericpressure in order that the solvent will not be carried overhead alongwith the conjugated diene, e.g., 1,3-butadiene, during the treatingprocess.

Glycols, amines, or thiols used as solvents having from 2-20 carbonatoms per molecule can be employed according to the invention. Varioustypes of materials that can be used as solvents include alkyleneglycols, polyalkylene glycols, primary amines, secondary amines,polyamines, monothios, dithiols, and mixtures of any of these materials.

Alkylene glycols and polyalkylene glycols that can be employed in theinvention are represented by the formula HOR-OH where R is an alkyleneradical, straight or branched chain, or an alkylene radical in which oneor more O- groups is substituted for one or more carbon atoms and eachpair of oxygen atoms is separated by at least two carbon atoms.Illustrative of these compounds are the following:

1,2-ethanediol (ethylene glycol) 1,2-propanediol 1,3-propanediol1,4-butanediol 1,2-butanediol 1,3-butanediol 1,2-pentanediol1,5-pentanediol 2,3-pentanediol 2,4-pentanediol 1,6-hexanediol2,4-hexanediol 1,8-octanediol 4,5-octanediol 1,10-decanediol1,15-pentadecanediol 5,7-diisopropyl-5,7-hendecanediol 1,10-eicosanediol3-ethyl-2,4-pentanediol 3,6-di-n-propyl-1,5-nonanediol5,5,9,9-tetramethyl-6,8-hexadecanediol 3-oxa-1,5-pentanediol (diethyleneglycol) 3,6-dioxa-1,8-octanediol (triethylene glycol)4,8,12-trioxa-1,15-pentadecanediol 5,10,15-trioxa-1, S-nonadecanediol3,9,l5-trimethyl-6,l2-dioxa-l,17-heptadecanediol 2,5 ,8, 11-tetramethyl-3,6,9, l 2-tetroxa-1, 14-pentadecanediol and the like.

Primary and secondary amines that can be employed 3 according to theinvention are represented by the formulas R'NH and where R is ahydrocarbon radical selected from the group consisting of saturatedaliphatic, saturated cycloaliphatic, and aromatic radicals, and mixturesthereof. Illustrative of these compounds are the following:

l-aminopentane (n-amylamine) N-methyl-2-aminopentane di-n-propylaminen-Hexylamine diisobutylamine 4-aminoheptane di-n-butylamineZ-aminohendecane l-amino do decane laminopentadecane S-aminoheptadecanel-aminoheptadecane l-aminoeicosane 4, 8-di-n-butyl-6-amino dodecane1-arninoeicosane N-n-amyl-S-aminononaneN-tert-butyl-S-amino-3,7-dimethyldecane eyclohexylamineN-methylcyclohexylamine N-n-amyl-1-amino-3,4-di-n-amylcyclopentaneaniline N-methylaniline N-ethyl-4-dodecylphenylamine 2,4,6-tri-n-propylphenylarnine benzylamine l-aminonaphthalene4,5-diethyl-Z-aminonaphthalene N-ethyl-l-naphthylamine3-phenylpropylamine u,a-dimethylbenzyl:amine3-(3,5-di-n-butylphenyl)propylamine and the like.

Polyamines that can be employed according to the invention arerepresented by the formula RI RI! NRN H u wherein R" is a straight orbranched chain alkylene, cycloalkylene, or arylene radical which cancontain one or more groups, or an alkylene radical in which one or moreII I groups is substituted for one or more carbon atoms with each pairof nitgrogen-containing groups separated by at least two carbon atoms,and R is as hereinbefore defined. Illustrative of these compounds arethe following:

ethylenediamine 1,2-diami11oethane) 1,3--diaminopropane1,3-diaminobutane 1,5 -diaminopentane 2,5-diaminoheptane1,10-diamin0decane 1,2,3-triaminopropane 1,5,9-triaminopentadeeaneN,N-di-n-amyl-1,7-diaminoheptane N -cyclohexyl-5 aminotetradecane 4;1,20-diaminoeicosane 1,4-diaminoeyclohexaneN,N'-di-n-hexyl-1,4-diaminocyclooctane 1, 3-diaminobenzene N-methyll,S-diaminonaphthalene diethylenetriamine triethylenetetraminetetnaethylenepentamine heptaethyleneoctamine N,N,N-trimethyl-4,8,12-triaz0pentadecane N-(4-cyclohexyl) 1,12-diaminododecaneN,N'-diphenyl- 1, 8-diaminooctane N,N-di( 4-tolyl) -2,4-diaminohexaneN-benzyll-aminonon ane and the like.

Monothiols and dithiols that can be employed according to the inventionare represented by the formulas RSH and HSR"SH where R is ashereinbefore defined and R is a straight or branced chain alkylene,cycloalkylene, or arylene radical. Illustrative of these compounds arethe following:

Z-butanethiol Z-methyl- 1-butanethiol 3-methyl-1-butanethiol 3-hexanethiol l-dodecanethiol 5 -pentadecanethiol l-tetradecanethioll-octadecanethiol 10-eicosanethiol 3 -phenyl-3-hexanethiol 6-(4-tolyl)l-hexanethiol 1,8-dicyclohexyl-4-octanethiolS-cyclopentyl-l-dodecanethiol 3,5 ,7-triethyl-l-nonanethiol1,2-ethanedithiol v 1,3-propanedithiol 1,4-butanedithiol 1,8-0etanedithiol 1,12-do decanedithiol 3 ,6-diethyl-3 ,6-octanedithiol 5- 3,S-dimethylphenyl) 3, 1 O-dodecanedithiol 3-cyclohexyl-1,6-hexanedithiol1,2-b enzenedithiol 1,4-cyelohexanedithiol and the like.

The concentration of the alkali metal hydroxide treating solutionaccording to the invention will depend on its solubility in theparticular solvent utilized. Generally, the concentration will be in therange of 0.1 to 1 molar, but can be outside this range when desired.

The rate of introduction or contact time for the conjugateddiene-containing stream being treated can vary over a considerablerange. When passing a gaseous conjugated diene stream through a solutionof a treating agent, flow rates are generally in the range of 0.2 to 10gas volumes per volume of treating solution per hour, preferably in therange of 0.5 to 5 gas volumes per volume of treating solution per hour.Flow rates outside these ranges can be used when desired.

Treating temperatures generally are in the range of l00250 C.,preferably in the range of l25-200 C. The treating temperature is atleast C. The process can 'be conducted at atmospheric orsuperatmospherie pressure.

This invention is of particular importance for purifying by-productbutadiene streams to render the butadiene suitable for use in, say,organo-metallic polymerization systems. The process of the invention canbe used to replace the separate steps of selective hydrogenation ofacetylenes and subsequent fractionation to remove 1,2- dienes. Aftertreatment according to the invention, light ends can be removed asdesired by conventional methods, including fractionation and other knownprocedures.

Monomer streams treated according to the invention comprise conjugateddienes containing from 4-10 inclusive carbon atoms. Examples ofconjugated dienes which can be used include 1,3-butadiene 52-methyl-1,3-but-adiene (isoprene) 2,3-dimethyl-1,3-butadiene1,3-pentadiene 2-methyl-1,3-pentadiene 2,3-dimethyl-1,3-pentadiene3-methyl-1,3-pentadiene 2-phenyl-l,3-but-adiene and the like.

This invention is applicable .to the polymerization of the above-definedconjugated dienes either alone or in admixture with each other and/orwith one or more compounds containing an active CHFC group which arecopolymerizable therewith.

After treatment of the conjugated dienes with the alkali metal hydroxidesolution of a glycol, amine or thiol as defined herein, thepolymerization is effected by contacting the conjugated dienes with apolymerization catalyst. Catalysts that can be used in the practice ofthe process of this invention are, in general, those which are efiectivefor polymerizing conjugated dienes to solid polymers. It is oftenpreferred to employ a catalyst comprising a member selected from thegroup consisting of organo metals or metal hydrides. However, othercatalysts can be used when desired. The process itself can be carriedout under well-known polymerization conditions.

Specific example A sample of by-product butadiene obtained from naphthacracking containing 1,2-dienes and acetylenes was purified by passing itthrough a 0.1 molar solution of potassium hydroxide in ethylene glycol.Eight treaters were arranged in series, each containing a portion of theKOH-glycol mixture. A flow meter was provided at the inlet to .thetreating train to measure the flow rate of the gaseous butadienemixture. Temperature was maintained at 160 C. throughout the operation.The gaseous butadiene stream was passed through the treating train atthe rate of approximately 0.78 gas volume per volume of treatingsolution per hour. A GLC analysis was run on the original material andalso on the treated product. The following table gives amounts of the1,2-dienes and l-acetylenes before and after treatment and also showsthe percentage reduction in quantities of the various materials as aresult of the treatment.

After Treatment Percent Reduction Before Treatment 1,3-Butadiene,Percent 34. Allene, Percent 0. Methylacetylene, Percent.-. 0Vinylacetylene, Percent. 0 l-Butyne, p.p.m 1,2-Butadiene, p.p.m

alkali metal hydroxide solution of a glycol, amine or thiol, or amixture of these at a temperature of at least C. as the contactingtemperature.

I claim:

1. A process for separating polyenes and acetylenic compounds from aconjugated diene mixture containing same which comprises contacting saidmixture at a temperature above 100 C. with an alkali metal hydroxidesolution of a compound selected from the group consisting of alkyleneand polyalkylene glycols, primary, secondary and polyamines having from2-20 carbon atoms per molecule, and mixtures of these.

2. A process according to claim 1 wherein said mixture comprisesbutadiene.

3. A process for separating 1,2-dienes and l-acetylenes from aconjugated diene mixture containing same which comprises contacting saidmixture at a temperature in the range of 100250 C. with a 0.1 to 1 molaralkali metal hydroxide solution of a compound selected from the groupconsisting of alkylene and polyalkylene glycols, primary, secondary andpolyamines having from 22() carbon atoms per molecule, and mixtures ofthese.

4. A process for separating 1,2-dienes and l-acetylenes from1,3-butadiene stream containing same which comprises passing said streamat a temperature in the range of 200 C. in the gaseous state through 0.1to 1 molar alkali metal hydroxide solution of a compound selected fromthe group consisting of alkylene and polyalkylene glycols, primary,secondary and polyamines having from 2-20 carbon atoms per molecule.

5. A process according to claim 4 wherein said alkali metal is selectedfrom sodium and potassium.

6. A process for separating 1,2-dienes and l-acetylenes from a1,3-butadiene stream containing same which comprises passing said streamat a temperature in the range of 125-200 C. in the gaseous state througha potassium hydroxide-ethylene glycol mixture.

7. A process for separating 1,2-dienes and l-acetylenes from aLil-butadiene stream containing same which comprises passing said streamat a temperature in the range of 125-200 C. in the gaseous state througha potassium hydroxide-triethylenetetramine mixture.

8. A process for separating 1,2-dienes and l-acetylenes from aconjugated diene mixture containing same which comprises passing saidmixture at a temperature in the range of IOU-250 C. through a series ofcontacting zones containing an alkali metal hydroxide solution of acompound selected from the group consisting of alkylene and polyalkyleneglyools, primary, secondary and polyamines having from 2-20 carbon atomsper molecule, and mixtures of these.

9. A process of purifying a C -C conjugated diene polymerization feedcontaining polyenes and acetylenic compounds that are contaminants inthe subsequent polymerization which comprises contacting said feed at atemperature above 100 C. with a 0.1 to 1 molar alkali metal hydroxidesolution of a compound selected from the group consisting of alkyleneand polyalkylene glycols, primary, secondary and polyamines having from2-2() carbon atoms per molecule, and mixtures of these, to remove saidcontaminants under conditions to selectively remove said contaminants,and then subjecting said feed substantially freed of contaminants topolymerization conditions.

10. A process according to claim 9 wherein said conjugated diene isbutadiene and said contaminants are selected from 1,2-dienes andl-acetylenes.

No references cited.

DELBERT E. GANTZ, Primary Examiner.

G. E. SCHMITKQNS, Assistant Examiner.

1. A PROCESS FOR SEPARATING POLYENES AND ACETYLENIC COMPOUNDS FROM ACONJUGATED DIENE MIXTURE CONTAINING SAME WHICH COMPRISES CONTACTING SAIDMIXTURE AT A TEMPERATURE ABOUT 100*C. WITH AN ALKALI METAL HYDROXIDESOLUTION OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKYLENEAND POLYALKYLENE GLYCOLS, PRIMARY, SECONDARY AND POLYAMINES HAVING FROM2-20 CARBON ATOMS PER MOLECULE, AND MIXTURES OF THESE.